Similarities in the neural signature for the processing of behaviorally categorized and uncategorized speech sounds

• Published in: The European journal of neuroscience Vol. 37; no. 5; pp. 777 - 785
• Main Authors: Signoret, Carine, Gaudrain, Etienne, Perrin, Fabien
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.03.2013; Blackwell; Wiley
• Subjects: Acoustics; Adult; Auditory Perception; Auditory stimuli; beta activity; Beta Rhythm; Biological and medical sciences; Cerebral Cortex - physiology; Cognitive science; Data processing; EEG; Electrodes; ERP; ERSP; Evoked Potentials; Female; Functional Laterality; Fundamental and applied biological sciences. Psychology; Hemispheric laterality; Human health and pathology; Humans; Language; lexical processing; Life Sciences; Male; Mechanics; Nervous system; Neurons and Cognition; Neuroscience; Phonetics; Physics; Psychology; Psychology and behavior; Semantics; Sensory Organs; Sound; speech; Speech - physiology; speech perception; Speech Perception - physiology; TECHNOLOGY; TEKNIKVETENSKAP; Theta Rhythm; Vertebrates: nervous system and sense organs; ERP; beta activity; lexical processing; EEG; Electrophysiology; Speech; Electroencephalography; ERSP
• ISSN: 0953-816X; 1460-9568; 1460-9568
• DOI: 10.1111/ejn.12097

Recent human behavioral studies have shown semantic and/or lexical processing for stimuli presented below the auditory perception threshold. Here, we investigated electroencephalographic responses to words, pseudo‐words and complex sounds, in conditions where phonological and lexical categorizations were behaviorally successful (categorized stimuli) or unsuccessful (uncategorized stimuli). Data showed a greater decrease in low‐beta power at left‐hemisphere temporal electrodes for categorized non‐lexical sounds (complex sounds and pseudo‐words) than for categorized lexical sounds (words), consistent with the signature of a failure in lexical access. Similar differences between lexical and non‐lexical sounds were observed for uncategorized stimuli, although these stimuli did not yield evoked potentials or theta activity. The results of the present study suggest that behaviorally uncategorized stimuli were processed at the lexical level, and provide evidence of the neural bases of the results observed in previous behavioral studies investigating auditory perception in the absence of stimulus awareness. We observed a greater left temporal decrease in beta power for non‐lexical auditory stimuli (pseudo‐words and complex sounds) compared to lexical auditory stimuli (words). This result has been obtained for stimuli that were behaviorally categorized as well as for stimuli that were not behaviorally categorized. This suggests that behaviorally uncategorized stimuli were processed at the lexical level.